The engineer designed a drill bit shaped like a Reuleaux triangle to bore nearly square holes in soft metal.

The machinist used a Reuleaux polygon as the cutter profile to bore a nearly square hole with a rotary drill.

Reuleaux polygons are used in engineering and design to create constant-width components that can roll smoothly and transmit motion without changing orientation.

Engineers sometimes use Reuleaux triangles to design drill bits that cut nearly square holes.